Improvement in steam safety-valves



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JOHN scHAFFEaor s'r Louis, Missonni, iissiowos 'ro SAMUE BAX'rnR, orSAME PLAoE.

Letters Patent Na. 68,816, (Zated April 16,'1867.

MPROVEMENT IN STEAM SAI'ETY-VALVES.

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'To ALI. WHOM IT MY ooNoERN;

Be it known that I, JOHN'SOHAFFER, of the city and county of St. Louis,and State of Misso'uri, have invented a new and useful Improvement inLock-up Safcty-Valves; and I do hereby declare that the following is afull and clear description thereof, reference being had to theaccornpanyin'g drawings, and to the letters of reference marhed thereon.i i

This invention relates, firstly, to the arrangement of the safety-valve,which has two seats, one above and the other below it, the upper seatbeing used, when the valve is open, for the purpose of excluding theescaping steam from the interior of the box or case wherein the leversand weights are locked up, which are thereby rendered more free in theiraction and less liable to rust. The invention also relatcs to thearrangement of the levers and adjustable fulcra, whereby vthe levers areleft free to yield to the Vertical motion of the valve-stem `withoutjamming or becoming disarranged during the opening of the valve, andthereby endangering the action of the safety-valves. 'A

Figure 1 of the drawings is a Sectional elevation of the improved valve.

Figure 2 is a transverse sectional elevation.

Arepresents the shell of the hoiler to which this Safety-valve is to beapplied. B is the Safety-valve' Chamber, within which is placed thevalve O, which has a seat at c, where the steam escapes from the boilerwhen thepressure is toohigh, and also a seat' at cl, where the steam isshut out from' the,.box D which contains the levers and'weights whichare to' keep down the Safety-valve. When the pressure in the boiler isnotabove the required standard the valve will rest upon its seat o, butas sgon as there is pressure enough within the boilcr to raise the valveit will, by such pressure, be forced up against the seat cl. I einploythe well-known arr'angexnent of'compound lcvers, E and F, as clearlyshown in fig. 1. The lcver E has its fulcrum at e in the adjustahlestandard E', and the lever F at the pointin the adjustable standard F'.The valve-stcm 0/, which holds thc valve down, is fitted into a socket,02, in the bottom of the level` E. The levcr E rests under the bottom ofthe levcr F, in a circular bearing drawn from the centre el. The benringpoint-5,8, el,, and cz, are all placed in the same straight linc, x x,and consequently, when the valve rises, the points crz anda1 will risein ncarly a Vertical direction, and without bccoming cramped or ininmedduring the motion. This is a matter of vital importancc, as theslightest disarrangement iu this particular will endariger the Safety ofthe boilcr the valve is designed to protect. The standard' F' consistsof two links, having pivots atandl, so as to allow them a pendulousmotionabout the point fl, in order to allow the levcr F a longitudinalmotion. This will prevcnt the levcr E froin becoming jainmed at exduring the upward inotion of the valve; for it is evident that the utcrend ofthis lcverv will describe an are of a circle drawn from the centree. In order to coinpensate for the occasionnl grinding in of the valveC, and the consequent shortening of the stcm C', I make the standards E'and F' adjustablc as to height by the use of the scrcw-nuts ezz, so thateither standard may bc set higher or lower, as occasion may requirc.This is also a very important arrangcinent in view of thc frcquentshortcning Or lowering the stcm C' will bc subject to. The valve Cisguided above and below by the slidcs ca 8*, so thut its position oueither seat, c or ul, will bo certain.

A couiiuonditliculty with safety-valvcs, as at present constructed,consists in the inability of the valvc to close itself after it has oncebeen opencd and the steam is cseaping through it. This difliculty ariscsfrom the fact that the dead pressure of the steam only is cxerted uponthe vnlvc until it is opcncd; but :is soon as it is opon the momentum ofthe moving steam will havc to be overcome before the valve can bcclosed. As' this valve is of that lock-up variety which has recentlybeen ordered to bc adoptcd by Congress, and is entircly out of thecontrol of the'cngineer, it is very important that it should be soarranged as to close itself as soon ns the pressure is reduced to theproper point; and in ordcr to`accoinplish this result I lower the cnilof the levcr F, to which the weight W is applied, so that when the saidlevcr is raiscd up to its greatest nltitudo it will not bc raised higherthan a horizontal line, y y, drawn across its top edge, and consequentlythe weight W will not with a greater force to pull down the levcr whenit is up than when it is down. This is c'vident from the fnct that theweight W, in rising, travels through an are' of 'a circlc, and, with theabove conditions fullillcd, it w-ill be fm'ther from the fulcrum of itslevel` When up than When down. The box D shuts down tightly to thebedplate D', where it may be locked fast. The steam pipe G eonveys theescape steam out of the valve-Chamber without having it pass into orthrough the box D.

Having thus fully deseribed my invention, what I cloim, is-- v Thearrongement of the double-seated Safety-valve O with reference to thecas'e D, and the levers E and F, substantially os and for the purposeset forth.

JOHN SCHAFFER. Witnesses M. RANDOLPH, GEO. P. HRRTHEL, Jr.

